Control device for motorized power steering device

Abstract

The present invention provides an electric power steering apparatus for controlling a motor based on a current command value calculated from a steering assist command value calculated based on a steering torque generated in a steering shaft and from a current detection value of the motor which gives a steering mechanism a steering assist force. In order to realize ideal road information sensitivity and steering feeling in frequency region at the same time, the electric power steering apparatus comprises a torque filter for processing a torque signal, an SAT estimating function, and an SAT filter for signal-processing SAT information from the SAT estimating function, and the electric power steering apparatus also comprises a control system with two degree of freedom which is capable of independently designing frequency characteristics of steering feeling and road information sensitivity.

Description

TECHNICAL FIELD[0001]The present invention relates to an electric power steering apparatus in which a steering assist force caused by a motor is given to a steering system of a car or a vehicle, and more particularly, to an electric power steering apparatus comprising a control system with two degree of freedom which is capable of independently designing steering feeling and road information sensitivity to realize ideal steering feeling and road information sensitivity at the same time in a frequency region.BACKGROUND TECHNIQUE[0002]The electric power steering apparatus for assist-load energizing the steering apparatus of a car or a vehicle with rotation force of a motor is designed to assist-load energize a steering shaft or a rack shaft with a driving force of the motor by a transmission mechanism such as a gear or a belt through a speed reducer. In such a conventional electric power steering apparatus, feedback control of motor current is performed to precisely generate assist to...

AI Technical Summary

Benefits of technology

The present invention is about an electric power steering system that controls a motor based on a current command value calculated from a steering assist command value and a current detection value of the motor. The system includes a torque filter, an SAT estimating function, and an SAT filter for signal-processing SAT information from the SAT estimating function. The system also has a control system with two degree of freedom that can independently design steering frequency characteristics of steering feeling and road information sensitivity. The invention effectively improves the steering feeling and eliminates unnecessary information in the road information sensitivity range.

Problems solved by technology

However, the conventional electric power steering apparatus has a problem that since the transmitting characteristics representing these two indices have mutual subordinative relation, it is difficult to design a control system which satisfies the two indices at the same time.

That is, since the steering feeling and the road information sensitivity have the mutual subordinative relation, the steering feeling and the road information sensitivity can not be designed independently, and it is difficult to design a control apparatus which satisfies the ideal steering feeling and road information sensitivity at the same time.

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